Set 2 pearl necklaces with 3 interchangeable clasps

Set 2 pearl necklaces with 3 interchangable clasps made of 18K WG+YG (24.1 gr), partly set with brilliant-cut diamonds in total ca. 0.16 ct, good colour a. clarity, Akoya cultured pearls ca. 6.5 mm with good lustre, necklace L: ca. 40 cm each, with additional spare pearls, 2nd half 20th century, minor signs of wear.